Electrical and Contractile Properties of the Heart Flashcards
Describe the conduction of excitation of the heart
Generated by the SA node, travels across the atria to the AV node, crossed the border between atria and ventricles at the bundle of his, conducted down the septum in bundle fibres which travel to the apex of the heart and then back up the ventricle walls as small branches purkinje fibres.
Why is the SA node is the dominant pacemaker
All heart cells able to generate spont. action potential and contractility but SA has highest frequency of this activity, so is always the first, its activity travels through the heart and shuts down the spontaneous activity of the rest of the heart. Secondary pacemaker, AV node, and later the ventricles themselves can replace the SA nodes activity if it is damaged.
